Oscillating motor circuit and switch



Oct. 27, 1959 E. T. SCHROTZBERGER 2,910,598

OSCILLATING MOTOR CIRCUIT AND SWITCH INVENTOR. 5 ,inm E0 WHPD TSCHROTZBERG'EI? BY HIS ATTORNEYS. HARRIS, K/lscH, Fos TEJ? & HARRIS Oct. 27, 1959 E. T. SCHROTZBERGER 2,910,598

OSCILLATING MOTOR CIRCUIT AND SWITCH Filed Nov. 14, 1955 2 Sheets-Sheet 2 lNl/LNTQR. 0 vvnfeo 7'. SCHROTZBLERGIR BY HIS HTTORNEYS. HARP/5, K/ecH, FOSTER & HARRIS United States Patent OSCILLATING MOTOR CIRCUIT AND swrrcn Edward T. Schrotzberger, Sierra Madre, Califi, assignor, by mesne assignments, to Beckman Instruments, Inc., Fullerton, Calif., a corporation of California Application November 14, 1955, Serial No. 546,436

7 Claims. (Cl. 310-89) The present invention relates in general to a device for producing and controlling movement and, more particularly, movement of an oscillatory member, such as a balance acting as the armature of an oscillating-motor. Such a motor will be considered herein as illustrative of a device to which the invention is applicable, with the understanding that the invention may have utility in other environments.

In general, an oscillating motor with which the present invention has utility may include an oscillatory armature or balance and electromagnetic means energizable periodically to oscillate the armature. Hairspring means, preferably an ordinary hairspring, constantly biases the armature toward a neutral position, corresponding to the relaxed position of the hairspring. The electromagnetic means is energized each time the armature arrives at the neutral position to rotate the armature away from .the neutral position in opposition to the action of the hairspring, the device providing mechanical switch means for energizing the electromagnetic means each time the armature is in its neutral position. This switch means includes a stationary contact and an oscillatory contact, the oscillatory contact engaging the stationary contact whenever the armature is in its neutral position and oscillating with the armature, as by being mounted thereon.

Thus, with a mechanism of the foregoing nature, the electromagnetic means is energized whenever the armature reaches its neutral position, due to the engagement ofv the oscillatory contact with the stationary contact. The energization of the electromagnetic means results in rotation of the armature away from its neutral position in opposition to the restoring action of the hairspring, which acts to return the armature to its neutral position when the energy imparted to the armature by the electromagnetic means has been absorbed. Such mechanisms may be used in various environments, such as in clocks, timers for control purposes, and the like.

In a device of the character hereinbefore outlined, since the hairspring is completely relaxed, or substantially so, when the armature is in its neutral position, only a very small force is available to urge the oscillatory contact into engagement with the stationary contact, the latter usually being a leaf spring past which the oscillatory contact moves. Consequently, when the armature is at rest in its neutral position, very low contact pressures exist between the oscillatory and stationary contacts, such low contact pressures resulting in contact resistances so high as to prevent starting of the oscillating motor in many instances. Also, when the armature is at rest, the oscillatory contact may be on either side of the stationary or leaf spring contact. Since the starting impulse provided by the electromagnetic means is unidirectional, it will be apparent that the starting impulse will tend to further reduce the contact pressure whenever the oscillatory contact is on one side of the stationary contact, even though it will tend to increase the contact pressure whenever the oscillatory contact is on the other side of the stationary contact.

Patented Oct. 27, 1959 To overcome problems such as these, others have re-' sorted to an external manual switch to short-circuit the oscillatory and stationary contacts momentarily in order to start the oscillating motor.

In view of the foregoing, a primary object of the invention is to provide a device having means for starting the oscillating motor automatically upon closure of the motor circuit, without resort to any external, manually operated switch for short-circuiting the afore-mentioned mechanical switch means. In other words, a primary object of the invention is to provide a self starting device.

More particularly, an important object of the invention is to provide a device which includes another switch means, in parallel with the aforementioned mechanical switch means, for automatically closing the motor circuit Whenever the armature is in its neutral position, such other switch means supplementing the mechanical switch means to insure "self starting of the motor, and acting as a standby motor switch to continue the operation of the device in the event of failure or malfunctioning of the mechanical switch means, which is a desirable safety feature in critical applications of the invention.

Another object is to provide a device wherein the other switch means mentioned is a magnetic switch means operative whenever the armature is in or near its neutral position.

Another object is to provide magnetic biasing means, operative when the armature is in thevicinity of its neutral position, for biasing the armature toward such position to produce closure of the magnetic switch means.

Another object is to provide such a magnetic biasing means which includes a magnet and means providing a substantially closed magnetic circuit for the magnet to attain maximum magnetic attraction.

With the foregoing construction, the magnetic biasing means supplements the action of the hai-rspring when the armature is in or near its neutral position, but does not interfere with the action of the hairspring when the armature has been rotated away from its neutral position by the electromagnetic means acting on the armature, which is an important feature.

Another object is to provide a magnetic switch means in which is incorporated the aforementioned magnetic biasing means for urging the armature toward its neutral position. Thus various elements of the magnetic switch means and the magnetic biasing means are common to both of these means, which is a feature of the invention.

Another object is to provide a magnetic biasing and switch means which includes a magnet connected to the armature so as to oscillate therewith, as by being mounted on the armature, and which includes two elements rela tively movable toward and away from each other, these elements having magnetizable portions respectively disposed on opposite sides of the path of the magnet so that relative movement of the elements toward each other occurs when the magnet is between such magnetizable portions, and these elements having electrically conductive, contact portions which engage when relative movement of the elements toward each other occurs in response to the presence of the magnet between the magnetizable portions of the elements.

With the foregoing construction, when the contact portions of the elements mentioned are in engagement, these elements provide, in effect, a yoke which spans the poles of the magnet to provide a substantially closed magnetic circuit having only two small air gaps, thereby attaining maximum magnetic attraction to bias the armature into its neutral position magnetically in a positive manner. More important, the contact portions of the elements described serve as switch contacts forming the magnetic switch means, which is connected to the oscillating motor in parallel with the aforementioned mechanical switch means to insure self starting. Further, the contact portions of these elements serve as stops which limit relative movement of the elements toward each other and which thus prevent mechanical interferences of theelemcnts with the oscillating magnet.

Preferably, the aforementioned elements of the magnetic biasing and switch means are rendered relatively movable toward and away from each other by making both elements movable. In this connection, an object of the invention is to make these elements cantilever spring arms having thereon the aforementioned magnetizable and contact portions.

The foregoing objects, advantages, features and results of this invention, together with various otherobjects, advantages, features and results thereof which will become apparent, may be attained with the exemplary embodiment of the invention which is illustrated in the accompanying drawings and which is described in detail hereinafter. Referring tothe drawings;

. Fig. 1 is a plan view, partially in section and with parts broken away, of a device which embodies the present invention;

Fig.2 is a vertical sectional view taken along the irregular arrowed line 22 of Fig. 1;

Fig. 3 is an enlarged, fragmentary sectional view taken along the arrowed line 3-3 of Fig. 1, with various parts of the device displaced from the positions shown in Fig. 1;

Fig. 4 is a diagrammatic plan view of the device illustrated in Figs. 1 to 3;

Fig. 5 is a diagrammatic elevational view corresponding to the diagrammatic plan view of Fig. 4; and

Figs. 6 and 7 are isometric views of components of the device of the invention.

Referring particularly to Figs. 1 and 2 of the drawing the numeral 10 designates a device which embodiesthe invention and which is shown as including a base 12 carrying a supporting structure, designated generally by the numeral 14, adapted to be enclosed by a hood 16 fitting over the base. The supporting structure 14 carries an oscillating motor 18 which includes electromagnetic means 20 for. producing oscillatory movement of an oscillatory armature or balance 22 in response to periodic energization of the electromagnetic means, the latter being shown as including an electromagnet 24 having a core 26 co-operating with the armature 22. The armature is mounted on a shaft 28 which is rotatably mounted in suitable bearings carried by the supporting structure 14. A hairspring 30 is anchored at one end to the shaft 28 and at its other end to the supporting structure 14, and biases the armature 22 toward a neutral or rest position, corresponding to complete relaxation, or substantially complete relaxation of the hairspring, the armature oscillating relative to this neutral position in response to periodic energization of the electromagnet 24.

The electromagnet 24 is energized whenever the armature is in its neutral position by a mechanical switch means 32, the latter being connected in series with the electromagnet and a battery 34, as shown in Fig. 5 of the drawings. Each time the armature 22 arrives in its neutral position, the switch means 32 energizes the electromagnet 24, which rotates the armature away from its neutral position in opposition to the action of the hairspring 36). When the energy imparted to the armature 22 by the electromagnet 24 has been absorbed by the hairspring, the latter returns the armature to its neutral position, whereupon the foregoing events are repeated.

The oscillatory movement of the armature 22 may be utilized to perform various functions. In the particular construction illustrated, the armature 22 operates an escapement mechanism 36, comprising an escapement wheel 38 engageable with means 40 on the armature shaft 28 for advancing the escapement Wheel incrementally in response to oscillation of the armature. The escapement Wheel drives an escapement shaft 42 having thereon 9.

rotor 44 provided with a contact 46, the contact having the form of a pin in the particular construction illustrated. The contact 46 engages a stationary contact 48, shown as a cantilever leaf spring mounted on the supporting structure 14, once per revolution of the rotor 44, the contacts 46 and 48 forming a switch means 50 for controlling an external circuit, not shown. Thus, in the particular construction illustrated, the device 10 functions as a direct current sequence timer for performing any desired control function. However, it will be understood that the oscillatory motion of the armature 22 may be utilized to perform various other functions.

Considering the switch means 32, it includes anoscillatory contact 52 connected to the armature 22 so as to oscillate therewith, preferably by mounting it directly on the armature, the oscillatory contact being a pin carried by the armature in the particular construction illustrated. When the armature '22 is in its neutral position, the

,oscillatory contact 52 engages a stationary contact 54 shown as having the form of a cantilever leaf spring mounted on an element 56 of the supporting structure 14. In the particular construction illustrated, the contact 52 is in electrically conductive relation with. the armature shaft 28, the armature shaft being grounded to the supporting structure 14 so that one side of the switch means 32 is connected to ground. The other side thereof is connected to ground through the battery 34 and the electromagnet 24 to complete the circuit.

With the foregoing construction, as long as the armature 22 is oscillating, its momentum carries the contact 52 into positive engagement with the contact 54 to provide the switch means 32 with minimum resistance. However, when the armature 22 is at rest, the hairspring 30 produces very little contact pressure between the contacts 52 and 54, due to the fact that the hairspring is completely relaxed, or nearly so. Consequently, under such conditions the resistance of the switch means is so high that the motor 18 may not start by itself, which is obviously undesirable.

In order to attain self starting of the motor 18 upon closure of the motor circuit, as by closure of a main switch 58, Fig. 5, the present invention provides magnetic switch means 62 in parallel with the switch means 32 to insure self starting of the motor and to provide a standby switch in the event of failure or malfunctioning of the switch means 32. The magnetic switch means 62 incorporates magnetic biasing means 60 for biasing the armature 22 into its neutral position in a positive manner.

Considering the magnetic biasing and switch means 60 and 62, a permanent magnet 64 is connected to the armature 22 so as to oscillate therewith, preferably by mounting the magnet directly on the armature in such a manner that it projects therethrough, as shown in the drawings. When the armature 22 is in its neutral position, the magnet is disposed between magnetizable, outwardly olfset portions 66 of cantilever leaf spring elements 68 and 69 mounted on a post 70 forming part of the supporting structure 14. As the magnet 64 moves between the outwardly offset portions 66, the magnet draws such portions toward each other, the spring elements 68 and 69 flexing to permit this. Motion of the spring elements 68 and 69 toward each other is limited by engagement of inwardly offset portions 72 of the spring elements to prevent contact between the magnet 64 and the outwardly offset portions 66. With this construction, when the inwardly offset portions 72 are pulled into engagement by traction is provided by the closed magnetic circuit to cause the magnet 64 to seek a position in which it is aligned with the outwardly offset portions'66 of the spring elements 68 and 69, these elements also providing the switch means 62. More particularly, the inwardly offset portions 72 the spring elements 68 and 69 act as contacts of the magnetic switch means 62, which is connected in series with the motor 18 and the battery 34, and in parallel with the mechanical switch means 32, as shown in Fig. 5 of the drawings. Considering the manner in which the magnetic switch means 62 is connected in the motor circuit, and referring particularly to Fig. 3 of the drawings, the leaf spring element 69 electrically engages an element 74 which in turn, electrically engages the post 70, the spring element 69 thus being grounded to the supporting structure 14. The element 74 takes the form of an inwardly curved finger which engages the inwardly offset portion 72 of the spring element 69 to limit movement of this spring element away from the other. The leaf spring element 68 is insulated from the element 69 and from the post 70 by insulating washers 76, the spring element 68 engaging an element 78, identical to the element 74, having the form of an inwardly curved finger which engages the inwardly offset portion 72 of the spring element 68 to limit movement thereof away from the other spring element. Thus, the elements 74 and 78 act as stops limiting movement of the leaf spring elements 68 and 69 away from each other. The assembly comprising the leaf spring elements 68 and 69, the elements 74 and 78, and the insulating washers 76, is clamped on the post 70 by means of a nut 80, and the spring element 6 8 is provided with a terminal 82, Fig. 6, which is connected to ground through the main switch 58, the battery 34 and the electromagnet 24. Thus, one side of the magnetic switch means 62 is grounded to the supporting structure 14 through the post 70 thereof, while the other side of this switch means is grounded to the supporting structure through the main switch 58, the battery 34 and the electromagnet 24 to complete this motor circuit, which is in parallel with the motor circuit through the mechanical switch means 32.

In order to increase the effectiveness of the closed magnetic circuit provided by the magnetic biasing means 60, the clearances between the outwardly offset portions 66 and the magnet 64 are kept to a minimum and the outwardly offset portions 66 are preferably made of a ma terial such as pure iron, or transformer iron having a high silicon content. Each spring element 68 and 69 may be made of such a material throughout, or only the yokeforming, outwardly offset portions 66 may be made thereof, the remainder of each spring element being made of a more resilient material having better electrical conductivity to provide a better spring action and less electrical resistance. Also, it will be understood that while the inwardly offset portions 72 of the spring elements 68 and 69 have been illustrated as acting as switch contacts directly, suitable contacts, not shown, mounted on the spring elements may be substituted for the inwardly offset portions 72 if desired.

It is thought that the over-all operation of the device disclosed will be apparent from the foregoing, so that only a brief description is required hereinafter. It will be understood that the magnet 64 co-operates with the spring elements 68 and 69 to bias the armature 22 toward its neutral position, the magnetic biasing means 60 aiding the hairspring 30. It will be noted that as soon as the magnet 64 moves far enough from the spring elements 68 and 69 to remove the field of the magnet from the vicinity of these elements, the magnetic biasing means 60 does not interfere with the normal action of the hairspring 30, the magnetic biasing means coming into operation only when the magnet is in the immediate vicinity of the spring elements 68 and 69. Since the spring elements 68 and 69 come into contact when the magnet 64 is inserted therebetween, a closed magnetic circuit is formed which provides maximum magnetic attraction to provide maximum bias of the armature 22 toward its neutral position. Also, the engagement between the spring elements 68 and .69 limits movement ofthese elements toward each other so that they donot contact the magnet, and, more important, such engagement between the spring elements 68 and 69 enables same-to co-operate'with the magnet 64 to provide the magnetic switch means 62. The latter, by providing an alternate motor-circuit, insures self starting of the motor 18, and also provides a standby switch means in the event of failure of the switch means 32. This latter is a safety feature which permits the device 10 to continue to operate even though the switch means 32 may cease to function, this feature being particularly important in critical applications of the device 10.

Although I have disclosed an exemplary embodiment of my invention herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims hereinafter appearing.

I claim as my invention:

. 1. In a device of the character described, the combination of: an oscillating motor including an oscillatory armature and electromagnetic means for oscillating said armature relative to a neutral position; switch means in series with said electromagnetic means; means responsive to movement of said armature into said neutral position for closing said switch means to energize said electromagnetic means periodically, whereby said electromagnetic means produces oscillatory movement of said armature; and magnetic means, including means forming a magnetic circuit through said armature composed sub stantially entirely of magnetizable material, for biasing said armature toward said neutral position, said magnetic means including a magnet connected to said armature so as to oscillate therewith, said magnetic-circuit-forming means including a yoke having arms respectively disposed on opposite sides of and closely adjacent the path of said magnet.

2. In a device of the character described, the combination of: an oscillating motor; and means for periodically energizing said motor, including mechanical switch means and magnetic switch means connected in parallel with each other and in series with said motor, and including means responsive to oscillation of said motor for closing said mechanical switch means and said magnetic switch means substantially simultaneously.

3. A device as defined in claim 1 wherein said arms of said yoke are relatively movable toward and away from each other and are provided with switch contacts which engage and disengage in response to relative movement of said arms toward and away from each other, said switch contacts forming another switch means which is connected in parallel with the switch means first mentioned.

4. In a device of the character described, the combination of: an oscillating motor having an armature oscillatory relative to a neutral position; a magnet connected to said armature so as to oscillate therewith; relatively movable elements having magnetizable portions disposed on opposite sides of the path of said magnet so that said magnet produces relative movement of said elements toward each other as it moves into the space therebetween, said elements having other portions relatively: movable into and out of contact with each other in response to relativemovement of said elements toward and away from each other, said other portions forming switch contacts; and means connecting said switch contacts in series with said oscillating motor.

5. In a device of the character described, the combination of: an oscillating motor including an oscillatory armature and electromagnetic means for oscillating said armature relative to a neutral position; first switch means 7 operable whenever .said' armature is in said" neutral position and connected in series with said electromagnetic means; and second, magnetic switch means operable whenever said armature is in said neutral position and connected in series with said electromagnetic means and in parallel withsaid first switch means.

6. A device as defined in claim 5 wherein said second switch means includes relatively movable switch contacts and magnetic means for closing said switch contacts whenever said armature is in said neutral position.

7. A device as defined in, claim 6 wherein said magnetic means includes a magnet connected to said armature and includes magnetizable elements connected to said switch contacts and adapted to receive said magnet therebetween.

References Cited in the tile of this patent VUNITEDNSTATES PATENTS Lindberg June 17, Henninger et al Dec. 16, Edelman Feb. 9, Adelson Apr. 6, Crise Sept. 7, Reitz May 22, Jones May 7,

FOREIGN PATENTS Switzerland May 1, 

